1. Field of the Invention
The present invention relates to agricultural spraying apparatus, and specifically to a spray boom suspension and lift assembly.
2. Description of the Prior Art
Liquid chemicals, such as fertilizer and insecticides, are commonly distributed by means of a spray apparatus carried on an applicator vehicle. Such spray apparatus generally has spray booms extending from each side of the applicator vehicle to permit distribution of the liquid chemical in as wide an area as possible for each pass of the applicator vehicle. By increasing the length of each boom, the spraying efficiency of the apparatus (in terms of both time and fuel) is substantially increased.
A number of problems are encountered when such booms are lengthened, however. For instance, it is usually necessary to transport such spray apparatus on public highways and through gates and openings in fences. Therefore, relatively long booms much be foldable against the applicator vehicle so that they do not interfere with the movement of the spray apparatus from one location to another. To this end, numerous boom designs have been developed which address this problem. Spray boom devices in which the booms are pivoted upwardly on horizontal axes to extend substantially vertical for transport are shown in the following United States Patents:
______________________________________ Inventor U.S. Pat. No. Issue Date ______________________________________ McClure et al 4,320,595 03/23/82 Reams 3,581,993 06/01/71 Loeffler 3,580,505 05/25/71 Blue et al 3,472,454 10/14/69 Young 3,301,487 01/31/67 Tygart 3,043,519 07/10/62 McMahon 2,995,307 08/08/61 Mueller et al 2,647,794 08/04/53 Black et al 2,273,344 02/17/42 ______________________________________
The lengths of the booms (or boom sections in the case of a foldable boom) are somewhat limited with the devices of these patents. Relatively long booms, when positioned for transport, would extend a substantial distance above the top of the applicator vehicle, thus precluding movement in an area where the vehicle must pass under overhead obstructions, such as low-hanging power lines or a bridge.
Spray boom devices where the booms are swung or folded to the side of the applicator vehicle to extend longitudinally thereon for transport or storage are shown in U.S. Pat. Nos. 4,221,353 granted to Kuhn et al. on Sept. 9, 1980; 4,038,147 granted to Hugg on Aug. 2, 1977; 3,447,750 granted to Weston on June 3, 1969; and 3,329,030 granted to Dijkhof on July 4, 1967. A side folding agricultural spray boom device is also shown in two promotional brochures of Blumhardt Manufacturing, Inc. of Ashley. N. Dak., which are both entitled "Blumhardt Pickup Mounted Sprayer." These devices show various means for folding the booms of such spray devices along substantially vertical axes to lie generally flat against the side of the vehicle. This is the preferred design for a relatively long multi-section boom since the sections of the boom can fold against each other and the vehicle for transport without significantly altering the usual lateral dimensions of the vehicle.
An additional consideration when the booms of a spray apparatus are relatively long is that the booms can, in effect, become powerful lever arms which act upon the applicator vehicle. Jarring motions of the vehicle, such as occur when it encounters a rut or hole in the field, cause the extended booms to bounce up and down. If a boom is of substantial length relative to the vehicle, relatively small vertical motions can result in bouncing of a large magnitude relative to the vehicle. To this end, devices have been developed to absorb the greater part of such bouncing impact from the booms to prevent undue strain on the spray apparatus and applicator vehicle. In U.S. Pat. Nos. 4,221,353 granted to Kuhn et al. on Sept. 9, 1980; 3,357,642 granted to Horton on Dec. 12, 1967; and the device shown in the Blumhardt brochures, the inner ends of the booms of these devices are mounted to pivot during operation, with the pivoting being controlled by spring-loaded rocker arms and shock absorbers operably connecting the booms to their respective central frames. These devices allow the booms to pivot on substantially horizontal axes relative to the applicator vehicle in a controlled state (because of the springs and shock absorbers) and absorb the bouncing or jarring motions of the booms as they react to changes in position of the applicator vehicle caused by uneven terrain.
It is sometimes necessary to tilt a boom relative to the applicator vehicle to allow the boom to clear an obstruction in the path of the boom. In the case of a horizontally folding boom, the boom must be provided with a means for tilting to boom. The device shown in U.S. Pat. No. 4,221,353 granted to Kuhn et al. on Sept. 9, 1980, is provided with manual means to tilt the boom to an upper clearance position. The necessity for manual actuation to raise the boom of this device could prove quite dangerous, since it necessarily requires distraction of the vehicle operator both physically and mentally from the normal motive operations of the applicator vehicle. The boom of this device has inner and outer sections with a resilient support mechanism between the inner section and the vehicle but having no such resilient support between the inner and outer sections. The structural portion of the vehicle upon which the booms are mounted is rigid and thus does not assist in the tilting of the booms.
U.S. Pat. Nos. 3,223,330 granted to La Plante on Dec. 14, 1965 and 869,958 granted to Bateman and Jones on Nov. 5, 1907 show spray boom devices where sliding elements on the main frame from which the booms are mounted results in movement of the booms. In the device shown in Bateman and Jones, the booms merely slide laterally upon the main frame for use, and therefore, are quite limited in their length. In the device of La Plante, a single horizontal slide on the main frame is connected to each of the booms so that movement of the slide transverse to the applicator vehicle causes one boom to be tilted upwardly and the other boom to be tilted downwardly. In these devices, a single sliding mechanisms are linked to both booms so that the booms are not independently movable or tiltable.
U.S. patents showing additional spray boom devices of interest include:
______________________________________ Inventor U.S. Pat. No. Issue Date ______________________________________ Greenburg 3,395,503 08/06/68 Dijkhof 3,731,879 05/08/73 Sunderman 3,554,478 02/12/71 Horstine Farmery 3,904,118 09/09/75 ______________________________________
None of these prior art devices show a boom assembly horizontally folding boom which is independently suspended from a main frame for floating action of the boom on a plurality of longitudinal axes and having a raising mechanism to selectively raise the boom by creating a force through the suspension means caused by pivoting portions of the main frame of the boom assembly. In addition, the boom assembly of the present invention is relatively inexpensive of manufacture, simple to maintain and repair, and sturdy of construction, as well as being easy to use and transport.